I visited this park with my in-laws during Chinese New Year. Though we only spent several hours, one could easily spend the entire day. They have nicely maintained trails which hike up to a small waterfall, then up and around the waterfall and back to the main area. We just did the up and back, but it is clear the long way around would be beautiful as well. There was a rest stop with bathrooms about half way up and picnic table/rest stops along the way.
Along the driveway, there are a number of displays of Taiwan insect life. If you have any interest at all in insects, this is an excellent, must-see attraction.
I understand that this park was built by the government then handed over to the local community for employment opportunities. There are a number of dams which control the water flow, but they were done in a way as to not appear too man-made. The water
The hot springs are an outdoor setting with multiple pools of various temperatures. Each pool has a sign of the temperature and PH balance of the water. The pools have different water massage elements, so you can move from station to station and get everything massaged. Of course, bathing caps are mandatory. The changing rooms are nice. If you don't bring your bathing cap, towel or need a locker, all are available at a price.
One of the great things about this park is that they do not accept tour buses, so crowds are kept at a minimum. Even at peak Chinese New Year time, there were just enough other guests to make it interesting.
This was a highlight of our trip and I encourage anyone in the area to spend at least a half-day.